add bell texts for future changes

What does this MR do?

Adds translations for possible future bells related to forum improvements.

How confident are you it won't break things if deployed?

100%

Links to related issues

https://beta.foodsharing.de/?page=bezirk&bid=2296&sub=forum&tid=223759&pid=1290171#post1290171

Screenshots (if applicable)

In the future this could look something like this:

Checklist

• no unrelated changes
• asked someone for a code review
• set a "for:" label to indicate who will be affected by this change
• added to the next milestone (see https://gitlab.com/foodsharing-dev/foodsharing/-/milestones, unless it has a "for:Dev" label)
• added an entry to CHANGELOG.md